S. bovis has long been associated with colorectal cancer (CRC),[2] however, not all genospecies are as closely related to CRC. A recent meta-analysis on the association between S. bovis biotypes and colonic adenomas/carcinomas revealed that patients with S. bovis biotype I infection had a strongly increased risk of having CRC (pooled odds ratio: 7.26; 95% confidence interval: 3.94–13.36), compared to S. bovis biotype II-infected patients.[11] This analysis clearly indicates that S. bovis should no longer be regarded as a single bacterial entity in clinical practice. Only Streptococcus gallolyticus (the new name of S. bovis biotype I) infection has an unambiguous association with colonic adenomas/carcinomas (prevalence range: 33–71%) that markedly exceeds the prevalence of colonic (pre-)maligancies in the general population (10–25%). Nonetheless, research has not yet determined if Streptococcus gallolyticus is a causative agent of colorectal cancer, or if pre-existing cancer makes the lumen of the large intestine more hospitable to its outgrowth.[12]

When ruminants consume diets high in starch or sugar, these easily fermentable carbohydrates promote the proliferation of S. bovis in the rumen. Because S. bovis is a lactic acid bacterium, fermentation of these carbohydrates to lactic acid can cause a dramatic decline in ruminal pH, and subsequent development of adverse conditions such as ruminal acidosis or feedlot bloat.[4][5]